Temperature Conversion: Mental Calculation (2014)
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Re: Temperature Conversion: Mental Calculation (2014)
#2Numerical implementations of functions often use look-up tables, and there's sometimes a trade-off between number of operations and memory access. (Large look-up tables aren't cache-friendly.)
This blog-post is from someone who prefers to do less mental arithmetic, but remember a few numbers: http://www.theexclusive.org/2012/08/converting-fahrenheit-in...
Re: Temperature Conversion: Mental Calculation (2014)
#3A much faster approximation that is not too far off over the range of everyday non-extreme temperatures:
C → F: times 2 then plus 30
F → C: minus 30 then divide by 2
Re: Temperature Conversion: Mental Calculation (2014)
#420 C > 68 F
30 C > 86 F
Re: Temperature Conversion: Mental Calculation (2014)
#5Numerical implementations of functions often use look-up tables, and there's sometimes a trade-off between number of operations and memory access. (Large look-up tables aren't cache-friendly.) This blog-post is from someone who prefers to do less mental arithmetic, but remember a few numbers: http://www.theexclusive.org/2012/08/converting-fahrenheit-in...
Thanks for sharing the theexclusive.org link. The trick discussed there is quite nifty. Here's a nice way to recall the lookup table mentioned there, in case, one forgets it:
- It is easy to remember that 0 °C = 32 °F because it is the freezing point of water.
- Every 10 °C interval corresponds to an interval of 18 °F. That's where the 9/5 in the conversion formula F = (9/5) * C + 32 comes from.
- Now it is easy to construct the lookup table: 10 °C = 50 °F, 20 °C = 68 °F, and 30 °C = 86 °F.
Re: Temperature Conversion: Mental Calculation (2014)
#620 C > 68 F 30 C > 86 F
-40 °C = -40 °F.
A related joke:
Saul: It's -40 outside.
Paul: Fahrenheit or Celsius?
Saul: When it's that cold, it's impossible to tell the difference.
Re: Temperature Conversion: Mental Calculation (2014)
#7For setting the a thermostat, it's not that hard to simply switch your brain over and know what's comfortable inherently in either F or C without doing a conversion back and forth. For accurate conversion, if c=(f-32)/1.8 or the converse is really that troublesome, Google can help you out.
Re: Temperature Conversion: Mental Calculation (2014)
#8My heuristic goes like this
20C ~ 70F (ok it's 68F but close enough)
a variation of +10F is +5C (same for minus)
Of course you can remember that 32F = 0C, that helps
Re: Temperature Conversion: Mental Calculation (2014)
#9A much faster approximation that is not too far off over the range of everyday non-extreme temperatures: C → F: times 2 then plus 30 F → C: minus 30 then divide by 2
This is what I use. I'm not quick with arithmetic in my head so if I want anything more accurate it's faster to just grab my phone.
Re: Temperature Conversion: Mental Calculation (2014)
#10If you know the stops of the 6 train in Manhattan, the trick is that the stops are in Fahrenheit starting at 33rd street = 0˚ C. Each stop up town is +5˚C. Stays within 1˚C until 110th street.